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Nitrogen Dioxide

General Description

Synonyms: Diesel exhaust component; Dinitrogen tetroxide (N2O4); NO2; Nitrogen peroxide; Nitrogen tetroxide

OSHA IMIS code: 1903

CAS number: 10102-44-0

Exposure Limits and Health Effects (Updated September 6, 2012)

Standard Set By Exposure Limit Health Effect Codes -- Health Effects and Target Organs
OSHA PEL - General Industry
See 29 CFR 1910.1000 Table Z-1
5 ppm (9 mg/m3) TWA
HE10 -- chronic bronchitis, emphysema
HE15 -- eye, nose, and upper respiratory irritation
OSHA PEL - Construction Industry
See 29 CFR 1926.55 Appendix A
5 ppm (9 mg/m3) TWA
HE10 -- chronic bronchitis, emphysema
HE15 -- eye, nose, and upper respiratory irritation
OSHA PEL - Shipyard Employment
See 29 CFR 1915.1000 Table Z - Shipyards
5 ppm (9 mg/m3) TWA
HE10 -- chronic bronchitis, emphysema
HE15 -- eye, nose, and upper respiratory irritation
NIOSH REL 1 ppm (1.8 mg/m3) STEL HE7 -- mild headache
HE10 -- bronchiolitis obliterans
HE11 -- acute pulmonary edema; lower respiratory irritation (cough, dyspnea)
HE15 -- eyes, nose, and throat irritation
ACGIH TLV® (2011) 0.2 ppm (0.38 mg/m3) TWA
HE11 -- lower respiratory irritation
CAL/OSHA PELs 1 ppm (1.8 mg/m3) STEL  

Carcinogenic classification:

  • NTP: Not listed
  • IARC: Not listed
  • EPA: Not listed

EPA Inhalation Reference Concentration (RfC): Not established

ATSDR Inhalation Minimal Risk Levels (MRLs): Not established

NIOSH IDLH concentration: 20 ppm

Notes on other potential health effects and hazards:

  1. Nitrogen dioxide may increase bronchoconstriction in asthmatics at concentrations as low as 0.1 ppm (Roger et al. 1990).
  2. Nitrogen dioxide is a component of silo gas thought to cause the sometimes fatal "silo filler's disease" (Douglas et al. 1989).
  3. Nitrogen dioxide itself is not combustible, but it may enhance the combustion of other chemicals (NIOSH/IPCS 2003).
  4. Nitrogen dioxide may exert an allergic response on the bronchial epithelium and may predispose the respiratory tract to viral infections (Pathmanathan et al. 2003; Frampton et al. 2002).
  5. NO2 exposure may reduce bronchociliar activity (Helleday et al. 1995).
  6. Even at low exposures, NO2 may increase asthmatic exacerbations following respiratory infections (Linaker et al. 2000).

Partial reference list:

  • ACGIH: Threshold Limit Values (TLVs) and Biological Exposure Indices (BEIs) - Nitrogen Dioxide. 2016.
  • Douglas, W.W., Hepper, N.G., and Colby, T.V.: Silo-filler's disease. Mayo Clin. Proc. 64(3): 291-304, 1989.
  • Frampton, M.W., Boscia, J., Roberts, N.J. Jr., Azadniv, M., Torres, A., Cox, C., Morrow, P.E., Nichols, J., Chalupa, D., Frasier, L.M., Gibb, F.R., Speers, D.M., Tsai, Y., Utell, M.J.: Nitrogen dioxide exposure: effects on airway and blood cells. Am J Physiol Lung Cell Mol Physiol. 282(1):L155-65, Jan 2002.
  • Helleday, R., Huberman, D., Blomberg, A., Stjernberg, N., Sandstrom, T.: Nitrogen dioxide exposure impairs the frequency of the mucociliary activity. Eur Respir J. 8(10):1664-8, Oct 1995.
  • Linaker, C.H., Coggon, D., Holgate, S.T., Clough, J., Josephs, L., Chauhan, A.J., Inskip, H.M.: Personal exposure to nitrogen dioxide and risk of airflow obstruction in asthmatic children with upper respiratory infection. Thorax. 55(11):930-3, Nov 2000.
  • NIOSH: Criteria for a Recommended StandardOccupational Exposure to Oxides of Nitrogen (Nitrogen Dioxide and Nitric Oxide). 1976.
  • NIOSH: Occupational Health Guideline for Nitrogen Dioxide. 1978.
  • NIOSH/CEC/IPCS: International Chemical Safety CardsNitrogen dioxide. 2003.
  • Pathmanathan, S., Krishna, M.T., Blomberg, A., Helleday, R., Kelly, F.J., Sandstrom, T., Holgate, S.T., Wilson, S.J., Frew, A.J.: Repeated daily exposure to 2 ppm nitrogen dioxide upregulates the expression of IL-5, IL-10, IL-13, and ICAM-1 in the bronchial epithelium of healthy human airways. Occup Environ Med. 60(11):892-6, Nov 2003.
  • Roger, L.J., Horstman, D.H., McDonnell, W., Kehrl, H., Ives, P.J., Seal, E., Chapman, R., Massaro, E.: Pulmonary function, airway responsiveness, and respiratory symptoms in asthmatics following exercise in NO2. Toxicol Ind Health. 6(1):155-71, Jan 1990.

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